Alternating-current electricity meter



Dec. 14,1926. I 1,611,103

s. 2. DE FERRANTI ALTERNATING CURRENT ELJECTBICITY METER.

, Filed FebQzs. 192 4 up I i r f mvemar I Fatented -Dec. 14,1926.

snensrmiv ZIANI b r nn mrirr, or r-rorrrnwoon, nlvernnnnssrenon To ran- 'RANTI, LIMITED, or H0LLlNW0OD, LANCASTEB,:E1\IGLAND. I

ALTERNATING-CTIBRENT nr nornrcrrynnrnn. 1

Application fiiear br r as, 1924, Serial No. 695,863, and in Great Britain June 29, 1923.

This invention relates to improvements in and relating to alternating current electricity meters of thewatt-hour induction motor type. In thesemeters, accuracy of record- 1ng under variations 1n load suffers on account of the falling characteristic which such meters possess. a

The drooping characteristic in-due to the fact that the series field has a braking effect upon the rotor of the meter; the series field naturally varieslwith variation in load 'curthe compensation of this variation in braking efiect. I I

The lnventlon consists in an electricity meter of the type described including in combination a shunt magnetic field circuit, a

series magnetic field circuit, a rotor member; rotated by the mutual interaction of said fields and a shaded pole induction motor element 'coacting with said rotor member to producean auxiliary drivin torque whose magnitude varies with variation in loadcurrent.

Referring to the accompanying diagram-v matic drawings V Y Figure 1 represents a. plan view partly in section of one convenient construction in of a-furthermodification;

. spon 'ng to Figure 5;

accordance with the present invention;

Figure 2 1s a slde elevatlonal v1ew corresponding to Figure 1; I

Figure 3 is a plan view partly in section of a modification;

Figure 4 is a side elevational view corresponding to Figure 3; V

Figure 5 is a plan View partly .in section Fi ure 6 is a side elevational view, corre- Figure I of a still further modification, and

- Figure 8 is a side elevational view corresponding to Figure 7. v

In carrying the invention into efiect in one form'by way of example, I provide an auxiliary motor element which co-operates with the main disc or other form of rotor or may co-operatewith an additional rotor provided on the meter spindle. This auxiliary motor element comprises conveniently a C shaped electromagnet a (Figures 1 7 is a plan view partly in section and 2) whose 'polepieces b and 0 rest respectively above and below the rotordisc d and which is energized'by an electromagnet coil e connected in series with the ordinary series circuit ofthe meter. Naturally this coil may, if desired, be connectedin a subsidiarycircuit or, may be otherwise excited,

provided that'it produces a field whose mag nitude is at all times substantially proportional to the load current of the meter. The

pole pieces are bifurcated and one of each of the bifurcations is furnished. with-a pair of copper rings 7, thus producing in operation a driving torque which increases with increase in load current. 1 p If deslred, one only of the pole pieces ma be bifurcated and provided with conducting '7 7 rings or oneor both of the poles maybe otherwiseshaded to produce a similar effect. According to a modification, instead of providing an additional electromagnet, I modify the normal series electromagnet core so that it" may furnish the necessary'auxiliary driving torque in accordance with the present invention. ,In this example (Fig- 80 ures 3 and 4) as applied to that form of the well-known Ferranti alternating current induction motor meter which embodies a'threelimb shunt electromagnet and a' U-shaped series electromagnet g disposed on opposite sides of a disc rotor, I bifurcate both pole pieces of the series electromagnet core '9 and.

' provide on one of each bifurcationsyanem circling conducting ring 7. By thismeans, although increase in, load current through the meter unavoidably increases the braking effect upon thel rotor, the latter is substantially neutralized by increased driving torque. V 7 According to a further modification-(Fig meter which embodies a thiee-limbed series one of the bifurcations withan encircling conducting ring f.

Figures 7 and 8 alljthree limbsare bifurcated andsimilarly provided with rings 7.

7 It is importantin all cases to 'so proportion and adjust the parts that shunt running does not take place. Y

'0. ures 5' and 6) asrapplied to that form of Ferranti alternating current induction motor According to thermodific'ation indicated in Having now described my invention what I claimpasnew and desire to secure by Letters Patent is A11 electricity meter of the type described including in combination a shunt-.mzignetic field circuit, a series magnetic field circuit, a rotor member rotatable bythe, interaction of said fields andadditionalmagnetic torque producingmeans comprising-u core term circuit and having a bifurcated poleformingprongs, and 2 v conducting member encircling one of said prongs, substantially as and for the p rposes set itorth.

In testimony whereof I have signed my meme to :this specification.

SEBASEIAN- ZIAN I 151a FE RRANTI. 

